Cannot make outgoing calls

You cannot use a telephone or telephones connected to the FRITZ!Box to make calls over the internet. This may also only occur with certain numbers you attempt to call. The problem either occurs sporadically or continuously. When it occurs, the telephone number may not be currently registered and one of the following error messages or a different message referring to the telephone number may be displayed in the event log of the FRITZ!Box:

If the status LED is still gray, contact your internet telephony provider to have your telephone number and account information checked.

4 The provider rejects the call attempt

This section only applies if the message "Internet telephony [...] failed. Reason for error: Not Acceptable Here (488)" is displayed under "System > Event Log" in the FRITZ!Box user interface when the error occurs. This message from your provider indicates that it does not make a requested function available for your line. This may be due to the following reasons, for example:

The provider does not support the requested codec.

The provider does not permit calls to the destination telephone number, for example calls to premium numbers.

The provider does not allow you to make simultaneous calls.

Therefore, the FRITZ!Box cannot resolve this issue.

5 Setting up the FRITZ!Box to conduct calls over another router

The following steps are only necessary if the FRITZ!Box does not establish its own connection to the internet, but instead uses the internet connection of another router in the network: